#include <crt_util.h>

static_inline void ev_rbtree_left_rotate(ev_rbtree_node_t** root, ev_rbtree_node_t* sentinel, ev_rbtree_node_t* node);
static_inline void ev_rbtree_right_rotate(ev_rbtree_node_t** root, ev_rbtree_node_t* sentinel, ev_rbtree_node_t* node);

ev_rbtree_node_t* ev_rbtree_min(ev_rbtree_node_t* node, ev_rbtree_node_t* sentinel)
{
    while (node->left != sentinel) {
        node = node->left;
    }

    return node;
}

void ev_rbtree_insert(ev_rbtree_t* tree, ev_rbtree_node_t* node)
{
    ev_rbtree_node_t **root, *temp, *sentinel;

    /* a binary tree insert */

    root = &tree->root;
    sentinel = tree->sentinel;

    if (*root == sentinel) {
        node->parent = NULL;
        node->left = sentinel;
        node->right = sentinel;
        ev_rbt_black(node);
        *root = node;

        return;
    }

    tree->insert(*root, node, sentinel);

    /* re-balance tree */

    while (node != *root && ev_rbt_is_red(node->parent)) {
        if (node->parent == node->parent->parent->left) {
            temp = node->parent->parent->right;

            if (ev_rbt_is_red(temp)) {
                ev_rbt_black(node->parent);
                ev_rbt_black(temp);
                ev_rbt_red(node->parent->parent);
                node = node->parent->parent;

            } else {
                if (node == node->parent->right) {
                    node = node->parent;
                    ev_rbtree_left_rotate(root, sentinel, node);
                }

                ev_rbt_black(node->parent);
                ev_rbt_red(node->parent->parent);
                ev_rbtree_right_rotate(root, sentinel, node->parent->parent);
            }

        } else {
            temp = node->parent->parent->left;

            if (ev_rbt_is_red(temp)) {
                ev_rbt_black(node->parent);
                ev_rbt_black(temp);
                ev_rbt_red(node->parent->parent);
                node = node->parent->parent;

            } else {
                if (node == node->parent->left) {
                    node = node->parent;
                    ev_rbtree_right_rotate(root, sentinel, node);
                }

                ev_rbt_black(node->parent);
                ev_rbt_red(node->parent->parent);
                ev_rbtree_left_rotate(root, sentinel, node->parent->parent);
            }
        }
    }

    ev_rbt_black(*root);
}

void ev_rbtree_insert_value(ev_rbtree_node_t* temp, ev_rbtree_node_t* node, ev_rbtree_node_t* sentinel)
{
    ev_rbtree_node_t** p;

    for (;;) {
        p = (node->key < temp->key) ? &temp->left : &temp->right;

        if (*p == sentinel) {
            break;
        }

        temp = *p;
    }

    *p = node;
    node->parent = temp;
    node->left = sentinel;
    node->right = sentinel;
    ev_rbt_red(node);
}

void ev_rbtree_insert_timer_value(ev_rbtree_node_t* temp, ev_rbtree_node_t* node, ev_rbtree_node_t* sentinel)
{
    ev_rbtree_node_t** p;

    for (;;) {
        /*
         * Timer values
         * 1) are spread in small range, usually several minutes,
         * 2) and overflow each 49 days, if milliseconds are stored in 32 bits.
         * The comparison takes into account that overflow.
         */

        /*  node->key < temp->key */

        p = ((ev_rbtree_key_int_t)(node->key - temp->key) < 0) ? &temp->left : &temp->right;

        if (*p == sentinel) {
            break;
        }

        temp = *p;
    }

    *p = node;
    node->parent = temp;
    node->left = sentinel;
    node->right = sentinel;
    ev_rbt_red(node);
}

void ev_rbtree_delete(ev_rbtree_t* tree, ev_rbtree_node_t* node)
{
    ev_int_t red;
    ev_rbtree_node_t **root, *sentinel, *subst, *temp, *w;

    /* a binary tree delete */

    root = &tree->root;
    sentinel = tree->sentinel;

    if (node->left == sentinel) {
        temp = node->right;
        subst = node;

    } else if (node->right == sentinel) {
        temp = node->left;
        subst = node;

    } else {
        subst = ev_rbtree_min(node->right, sentinel);
        temp = subst->right;
    }

    if (subst == *root) {
        *root = temp;
        ev_rbt_black(temp);

        /* DEBUG stuff */
        node->left = NULL;
        node->right = NULL;
        node->parent = NULL;
        node->key = 0;

        return;
    }

    red = ev_rbt_is_red(subst);

    if (subst == subst->parent->left) {
        subst->parent->left = temp;

    } else {
        subst->parent->right = temp;
    }

    if (subst == node) {
        temp->parent = subst->parent;

    } else {
        if (subst->parent == node) {
            temp->parent = subst;

        } else {
            temp->parent = subst->parent;
        }

        subst->left = node->left;
        subst->right = node->right;
        subst->parent = node->parent;
        ev_rbt_copy_color(subst, node);

        if (node == *root) {
            *root = subst;

        } else {
            if (node == node->parent->left) {
                node->parent->left = subst;
            } else {
                node->parent->right = subst;
            }
        }

        if (subst->left != sentinel) {
            subst->left->parent = subst;
        }

        if (subst->right != sentinel) {
            subst->right->parent = subst;
        }
    }

    /* DEBUG stuff */
    node->left = NULL;
    node->right = NULL;
    node->parent = NULL;
    node->key = 0;

    if (red) {
        return;
    }

    /* a delete fixup */

    while (temp != *root && ev_rbt_is_black(temp)) {
        if (temp == temp->parent->left) {
            w = temp->parent->right;

            if (ev_rbt_is_red(w)) {
                ev_rbt_black(w);
                ev_rbt_red(temp->parent);
                ev_rbtree_left_rotate(root, sentinel, temp->parent);
                w = temp->parent->right;
            }

            if (ev_rbt_is_black(w->left) && ev_rbt_is_black(w->right)) {
                ev_rbt_red(w);
                temp = temp->parent;

            } else {
                if (ev_rbt_is_black(w->right)) {
                    ev_rbt_black(w->left);
                    ev_rbt_red(w);
                    ev_rbtree_right_rotate(root, sentinel, w);
                    w = temp->parent->right;
                }

                ev_rbt_copy_color(w, temp->parent);
                ev_rbt_black(temp->parent);
                ev_rbt_black(w->right);
                ev_rbtree_left_rotate(root, sentinel, temp->parent);
                temp = *root;
            }

        } else {
            w = temp->parent->left;

            if (ev_rbt_is_red(w)) {
                ev_rbt_black(w);
                ev_rbt_red(temp->parent);
                ev_rbtree_right_rotate(root, sentinel, temp->parent);
                w = temp->parent->left;
            }

            if (ev_rbt_is_black(w->left) && ev_rbt_is_black(w->right)) {
                ev_rbt_red(w);
                temp = temp->parent;

            } else {
                if (ev_rbt_is_black(w->left)) {
                    ev_rbt_black(w->right);
                    ev_rbt_red(w);
                    ev_rbtree_left_rotate(root, sentinel, w);
                    w = temp->parent->left;
                }

                ev_rbt_copy_color(w, temp->parent);
                ev_rbt_black(temp->parent);
                ev_rbt_black(w->left);
                ev_rbtree_right_rotate(root, sentinel, temp->parent);
                temp = *root;
            }
        }
    }

    ev_rbt_black(temp);
}

static_inline void ev_rbtree_left_rotate(ev_rbtree_node_t** root, ev_rbtree_node_t* sentinel, ev_rbtree_node_t* node)
{
    ev_rbtree_node_t* temp;

    temp = node->right;
    node->right = temp->left;

    if (temp->left != sentinel) {
        temp->left->parent = node;
    }

    temp->parent = node->parent;

    if (node == *root) {
        *root = temp;

    } else if (node == node->parent->left) {
        node->parent->left = temp;

    } else {
        node->parent->right = temp;
    }

    temp->left = node;
    node->parent = temp;
}

static_inline void ev_rbtree_right_rotate(ev_rbtree_node_t** root, ev_rbtree_node_t* sentinel, ev_rbtree_node_t* node)
{
    ev_rbtree_node_t* temp;

    temp = node->left;
    node->left = temp->right;

    if (temp->right != sentinel) {
        temp->right->parent = node;
    }

    temp->parent = node->parent;

    if (node == *root) {
        *root = temp;

    } else if (node == node->parent->right) {
        node->parent->right = temp;

    } else {
        node->parent->left = temp;
    }

    temp->right = node;
    node->parent = temp;
}

ev_rbtree_node_t* ev_rbtree_next(ev_rbtree_t* tree, ev_rbtree_node_t* node)
{
    ev_rbtree_node_t *root, *sentinel, *parent;

    sentinel = tree->sentinel;

    if (node->right != sentinel) {
        return ev_rbtree_min(node->right, sentinel);
    }

    root = tree->root;

    for (;;) {
        parent = node->parent;

        if (node == root) {
            return NULL;
        }

        if (node == parent->left) {
            return parent;
        }

        node = parent;
    }
}
